FIELD OF THE INVENTION
The invention relates to a sanitary water fitting, particularly, in the form of a single handle mixer valve assembly with a control unit comprising discs, a piston, balls or the like, and with a damper for the closing action, to lengthen the closing time and reduce the closing speed.
Single handle mixer valve assemblies are usually provided with valve control units fitted with aluminum oxide discs, balls or pistons. They are generally provided with a handle in the form of a lever or a knob to adjust water volume and temperature. Such valve assemblies are increasing in popularity since they are simple to operate and can control the water volume and temperature rapidly.
An obvious step carried out for economic reasons and to simplify the installation is to keep the cross-sections of the pipes leading to the fittings as small as possible. Efforts in this direction are aided by use of plastic pipes, the so-called "pipe within pipe". Here, the source is a distributor serving one flat. Each fitting is separately connected and the cross-sections required to supply the fittings are relatively small in view of the flow volumes, accordingly, correspondingly high water speeds are encountered. If such installations are fitted with single handle mixer valve assemblies, which generally shut off water very quickly, this may result in pressure shock. On the one hand, these may make an annoying noise and, on the other hand, certain pressures must not be exceeded since there would otherwise be excessive strains on the components of the system. These pressure shocks are also known as "water hammer".
Water hammer may be corrected by reducing the rate of flow in the pipe, thereby reducing the sound level;
or by shortening the amplitude of the pressure wave, such as by providing means to increase time required to close the valve.
Reducing the flow velocity of a pipe is not desirable. The sound level of water flow achieved by plastic pipe water systems is lower than metal pipe and, therefore, cannot be reduced further. The pipe length has no effect on the length of the sound wave produced by the pipe. It is possible by use of air chamber-like fittings to reduce the inherent resonance of the pipe; however, this does not effect the sound level in the pipe. Piston pumps use such fittings and can be distributed over the length of the pipe; however, such fittings are expensive and are not reliable in operation because of possible air leakage in the system. It is possible to limit the increase time required to shut the valve by extending its actuating distance; however, this is not always desirable. Such devices to increase the closing time and to reduce the closing rate of the fittings are in the form of shock absorbers and are used in water supply systems, in industrial fittings, as well as in single handle mixer valve assemblies. A known assembly of this type, with control elements in disc form, provides for the movable sealing disc to be delayed by coupling a damper assembly to it. A disadvantage of such a solution is that the damper components inside the water fitting transmit sound created by naturally strong damping forces. Another disadvantage is that such a damper assembly for reducing the closing action is not easily repairable, nor is it generally replaceable.